Extracorporeal membrane oxygenation and cerebral blood flow velocity in children

Neuromonitoring in the ICU: noninvasive and invasive modalities for critically ill children and neonates

PURPOSE OF REVIEW

Critically ill children are at risk of neurologic dysfunction and acquiring primary and secondary brain injury. Close monitoring of cerebral function is crucial to prevent, detect, and treat these complications.

RECENT FINDINGS

A variety of neuromonitoring modalities are currently used in pediatric and neonatal ICUs. These include noninvasive modalities, such as electroencephalography, transcranial Doppler, and near-infrared spectroscopy, as well as invasive methods including intracranial pressure monitoring, brain tissue oxygen measurement, and cerebral microdialysis. Each modality offers unique insights into neurologic function, cerebral circulation, or metabolism to support individualized neurologic care based on a patient's own physiology. Utilization of these modalities in ICUs results in reduced neurologic injury and mortality and improved neurodevelopmental outcomes.

SUMMARY

Monitoring of neurologic function can significantly improve care of critically ill children. Additional research is needed to establish normative values in pediatric patients and to standardize the use of these modalities.

Neutrophils: a key component in ECMO-related acute organ injury

Extracorporeal membrane oxygenation (ECMO), as an extracorporeal life support technique, can save the lives of reversible critically ill patients when conventional treatments fail. However, ECMO-related acute organ injury is a common complication that increases the risk of death in critically ill patients, including acute kidney injury, acute brain injury, acute lung injury, and so on. In ECMO supported patients, an increasing number of studies have shown that activation of the inflammatory response plays an important role in the development of acute organ injury. Cross-cascade activation of the complement system, the contact system, and the coagulation system, as well as the mechanical forces of the circuitry are very important pathophysiological mechanisms, likely leading to neutrophil activation and the production of neutrophil extracellular traps (NETs). NETs may have the potential to cause organ damage, generating interest in their study as potential therapeutic targets for ECMO-related acute organ injury. Therefore, this article comprehensively summarized the mechanism of neutrophils activation and NETs formation following ECMO treatment and their actions on acute organ injury.

Brain development in newborns and infants after ECMO

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) not only significantly improves survival rates in severely ill neonates but also is associated with long-term neurodevelopmental issues. To systematically review the available literature on the neurodevelopmental outcomes of neonates and infants who have undergone ECMO treatment, with a focus on motor deficits, cognitive impairments, sensory impairments, and developmental delays. This review aims to understand the incidence, prevalence, and risk factors for these problems and to explore current nursing care and management strategies.

DATA SOURCES

A comprehensive literature search was performed across PubMed, EMBASE, and Web of Science using a wide array of keywords and phrases pertaining to ECMO, neonates, infants, and various facets of neurodevelopment. The initial screening involved reviewing titles and abstracts to exclude irrelevant articles, followed by a full-text assessment of potentially relevant literature. The quality of each study was evaluated based on its research methodology and statistical analysis. Moreover, citation searches were conducted to identify potentially overlooked studies. Although the focus was primarily on neonatal ECMO, studies involving children and adults were also included due to the limited availability of neonate-specific literature.

RESULTS

About 50% of neonates post-ECMO treatment exhibit varying degrees of brain injury, particularly in the frontal and temporoparietal white matter regions, often accompanied by neurological complications. Seizures occur in 18%-23% of neonates within the first 24 hours, and bleeding events occur in 27%-60% of ECMO procedures, with up to 33% potentially experiencing ischemic strokes. Although some studies suggest that ECMO may negatively impact hearing and visual development, other studies have found no significant differences; hence, the influence of ECMO remains unclear. In terms of cognitive, language, and intellectual development, ECMO treatment may be associated with potential developmental delays, including lower composite scores in cognitive and motor functions, as well as potential language and learning difficulties. These studies emphasize the importance of early detection and intervention of potential developmental issues in ECMO survivors, possibly necessitating the implementation of a multidisciplinary follow-up plan that includes regular neuromotor and psychological evaluations. Overall, further multicenter, large-sample, long-term follow-up studies are needed to determine the impact of ECMO on these developmental aspects.

CONCLUSIONS

The impact of ECMO on an infant's nervous system still requires further investigation with larger sample sizes for validation. Fine-tuned management, comprehensive nursing care, appropriate patient selection, proactive monitoring, nutritional support, and early rehabilitation may potentially contribute to improving the long-term outcomes for these infants.

The State of the Field of Pediatric Multimodality Neuromonitoring

BACKGROUND

The use of multimodal neuromonitoring in pediatrics is in its infancy relative to adult neurocritical care. Multimodal neuromonitoring encompasses the amalgamation of information from multiple individual neuromonitoring devices to gain a more comprehensive understanding of the condition of the brain. It allows for adaptation to the changing state of the brain throughout various stages of injury with potential to individualize and optimize therapies.

METHODS

Here we provide an overview of multimodal neuromonitoring in pediatric neurocritical care and its potential application in the future.

RESULTS

Multimodal neuromonitoring devices are key to the process of multimodal neuromonitoring, allowing for visualization of data trends over time and ideally improving the ability of clinicians to identify patterns and find meaning in the immense volume of data now encountered in the care of critically ill patients at the bedside. Clinical use in pediatrics requires more study to determine best practices and impact on patient outcomes. Potential uses include guidance for targets of physiological parameters in the setting of acute brain injury, neuroprotection for patients at high risk for brain injury, and neuroprognostication. Implementing multimodal neuromonitoring in pediatric patients involves interprofessional collaboration with the development of a simultaneous comprehensive program to support the use of multimodal neuromonitoring while maintaining the fundamental principles of the delivery of neurocritical care at the bedside.

CONCLUSIONS

The possible benefits of multimodal neuromonitoring are immense and have great potential to advance the field of pediatric neurocritical care and the health of critically ill children.

Cerebral Autoregulation: A Target for Improving Neurological Outcomes in Extracorporeal Life Support

Despite improvements in survival after illnesses requiring extracorporeal life support, cerebral injury continues to hinder successful outcomes. Cerebral autoregulation (CA) is an innate protective mechanism that maintains constant cerebral blood flow in the face of varying systemic blood pressure. However, it is impaired in certain disease states and, potentially, following initiation of extracorporeal circulatory support. In this review, we first discuss patient-related factors pertaining to venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) and their potential role in CA impairment. Next, we examine factors intrinsic to ECMO that may affect CA, such as cannulation, changes in pulsatility, the inflammatory and adaptive immune response, intracranial hemorrhage, and ischemic stroke, in addition to ECMO management factors, such as oxygenation, ventilation, flow rates, and blood pressure management. We highlight potential mechanisms that lead to disruption of CA in both pediatric and adult populations, the challenges of measuring CA in these patients, and potential associations with neurological outcome. Altogether, we discuss individualized CA monitoring as a potential target for improving neurological outcomes in extracorporeal life support.

Multimodal Neurologic Monitoring in Patients Undergoing Extracorporeal Membrane Oxygenation

Introduction Extracorporeal membrane oxygenation (ECMO) is associated with a high rate of neurologic complications. Multimodal neurologic monitoring (MNM) has the potential for early detection and intervention. We examined the safety and feasibility of noninvasive MNM during ECMO. We hypothesized that survivors and non-survivors would have meaningful differences in transcranial Doppler (TCD) sonography and electroencephalographic (EEG) characteristics, which we aimed to identify. We also investigated adverse neurologic events and attempted to identify differences in EEG and TCD characteristics among patients based on the type of ECMO and the occurrence of these events. Material and methods We performed an observational study on all patients undergoing ECMO at Baylor St. Luke's Medical Center's critical care unit in Houston, Texas, United States, from January 2017 to February 2019. All patients underwent a noninvasive MNM protocol. Results NM was completed in 75% of patients; all patients received at least one component of the monitoring protocol. No adverse events were noted, showing the feasibility and safety of the protocol. The 60.4% of patients who did not survive tended to be older, had lower ejection fractions, and had lower median right middle cerebral artery (MCA) pulsatility and resistivity indexes. Patients undergoing venoarterial (VA)-ECMO had lower median left and right MCA velocities and lower right Lindegaard ratios than patients who underwent venovenous-ECMO. In VA-ECMO patients, EEG less often showed sleep architecture, while other findings were similar between groups. Adverse neurologic events occurred in 24.7% of patients, all undergoing VA-ECMO. Acute ischemic stroke occurred in 22% of patients, intraparenchymal hemorrhage in 4.9%, hypoxic-ischemic encephalopathy in 3.7%, subarachnoid hemorrhage in 2.5%, and subdural hematoma in 1.2%. Conclusion Our results suggest that MNM is safe and feasible for patients undergoing ECMO. Certain EEG and TCD findings could aid in the early detection of neurologic deterioration. MNM may not just be used in monitoring patients undergoing ECMO but also in prognostication and aiding clinical decision-making.

Clinical Guidelines for Routine Neuromonitoring in Neonatal and Pediatric Patients Supported on Extracorporeal Membrane Oxygenation

DISCLAIMER

These guidelines for routine neuromonitoring in neonatal and pediatric patients supported on extracorporeal membrane oxygenation (ECMO) are intended for educational use to build the knowledge of physicians and other health professionals in assessing the conditions and managing the treatment of patients undergoing extracorporeal life support (ECLS)/ECMO and describe what are believed to be useful and safe practice for ECLS and ECMO but these are not necessarily consensus recommendations. The aim of clinical guidelines was to help clinicians to make informed decisions about their patients. However, adherence to a guideline does not guarantee a successful outcome. Healthcare professionals must make their own treatment decisions about care on a case-by-case basis, after consultation with their patients, using their clinical judgment, knowledge, and expertise. These guidelines do not take the place of physicians' and other health professionals' judgment in diagnosing and treatment of patients. These guidelines are not intended to and should not be interpreted as setting a standard of care or being deemed inclusive of all proper methods of care nor exclusive of other methods of care directed at obtaining the same results. The ultimate judgment must be made by the physician and other health professionals and the patient considering all the circumstances presented by the individual patient, and the known variability and biologic behavior of the clinical condition. These guidelines reflect the data at the time the guidelines were prepared; the results of subsequent studies or other information may cause revisions to the recommendations in these guidelines to be prudent to reflect new data, but ELSO is under no obligation to provide updates. In no event will ELSO be liable for any decision made or action taken in reliance upon the information provided through these guidelines.

Subtypes and Mechanistic Advances of Extracorporeal Membrane Oxygenation-Related Acute Brain Injury

Extracorporeal membrane oxygenation (ECMO) is a frequently used mechanical cardiopulmonary support for rescuing critically ill patients for whom conventional medical therapies have failed. However, ECMO is associated with several complications, such as acute kidney injury, hemorrhage, thromboembolism, and acute brain injury (ABI). Among these, ABI, particularly intracranial hemorrhage (ICH) and infarction, is recognized as the primary cause of mortality during ECMO support. Furthermore, survivors often suffer significant long-term morbidities, including neurocognitive impairments, motor disturbances, and behavioral problems. This review provides a comprehensive overview of the different subtypes of ECMO-related ABI and the updated advance mechanisms, which could be helpful for the early diagnosis and potential neuromonitoring of ECMO-related ABI.

International survey of neuromonitoring and neurodevelopmental outcome in children and adults supported on extracorporeal membrane oxygenation in Europe

BACKGROUND

Adverse neurological events during extracorporeal membrane oxygenation (ECMO) are common and may be associated with devastating consequences. Close monitoring, early identification and prompt intervention can mitigate early and late neurological morbidity. Neuromonitoring and neurocognitive/neurodevelopmental follow-up are critically important to optimize outcomes in both adults and children.

OBJECTIVE

To assess current practice of neuromonitoring during ECMO and neurocognitive/neurodevelopmental follow-up after ECMO across Europe and to inform the development of neuromonitoring and follow-up guidelines.

METHODS

The EuroELSO Neurological Monitoring and Outcome Working Group conducted an electronic, web-based, multi-institutional, multinational survey in Europe.

RESULTS

Of the 211 European ECMO centres (including non-ELSO centres) identified and approached in 23 countries, 133 (63%) responded. Of these, 43% reported routine neuromonitoring during ECMO for all patients, 35% indicated selective use, and 22% practiced bedside clinical examination alone. The reported neuromonitoring modalities were NIRS (n = 88, 66.2%), electroencephalography (n = 52, 39.1%), transcranial Doppler (n = 38, 28.5%) and brain injury biomarkers (n = 33, 24.8%). Paediatric centres (67%) reported using cranial ultrasound, though the frequency of monitoring varied widely. Before hospital discharge following ECMO, 50 (37.6%) reported routine neurological assessment and 22 (16.5%) routinely performed neuroimaging with more paediatric centres offering neurological assessment (65%) as compared to adult centres (20%). Only 15 (11.2%) had a structured longitudinal follow-up pathway (defined followup at regular intervals), while 99 (74.4%) had no follow-up programme. The majority (n = 96, 72.2%) agreed that there should be a longitudinal structured follow-up for ECMO survivors.

CONCLUSIONS

This survey demonstrated significant variability in the use of different neuromonitoring modalities during and after ECMO. The perceived importance of neuromonitoring and follow-up was noted to be very high with agreement for a longitudinal structured follow-up programme, particularly in paediatric patients. Scientific society endorsed guidelines and minimum standards should be developed to inform local protocols.

Neurological monitoring in ECMO patients: current state of practice, challenges and lessons

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) in critically ill patients serves as a management option for end-stage cardiorespiratory failure in medical and surgical conditions. Patients on ECMO are at a high risk of neurologic adverse events including intracranial hemorrhage (ICH), acute ischemic stroke (AIS), seizures, diffuse cerebral edema, and hypoxic brain injury. Standard approaches to neurological monitoring for patients receiving ECMO support can be challenging for multiple reasons, including the severity of critical illness, deep sedation, and/or paralysis. This narrative literature review provides an overview of the current landscape for neurological monitoring in this population.

METHODS

A literature search using PubMed was used to aid the understanding of the landscape of published literature in the area of neurological monitoring in ECMO patients.

RESULTS

Review articles, cohort studies, case series, and individual reports were identified. A total of 73 varied manuscripts were summarized and included in this review which presents the challenges and strategies for performing neurological monitoring in this population.

CONCLUSION

Neurological monitoring in ECMO is an area of interest to many clinicians, however, the literature is limited, heterogenous, and lacks consensus on the best monitoring practices. The evidence for optimal neurological monitoring that could impact clinical decisions and functional outcomes is lacking. Additional studies are needed to identify effective measures of neurological monitoring while on ECMO.

Functional Status Change Among Infants, Children, and Adolescents Following Extracorporeal Life Support: a Multicenter Report

In our retrospective multicenter study of patients 0 to 18 years of age who survived extracorporeal life support (ECLS) between January 2010 and December 2018, we sought to characterize the functional status scale (FSS) of ECLS survivors, determine the change in FSS from admission to discharge, and examine risk factors associated with development of new morbidity and unfavorable outcome. During the study period, there were 1,325 ECLS runs, 746 (56%) survived to hospital discharge. Pediatric patients accounted for 56%. Most common ECLS indication was respiratory failure (47%). ECLS support was nearly evenly split between veno-arterial and veno-venous (51% vs . 49%). Median duration of ECLS in survivors was 5.5 days. Forty percent of survivors had new morbidity, and 16% had an unfavorable outcome. In a logistic regression, African American patients (OR 1.68, p = 0.01), longer duration of ECLS (OR 1.002, p = 0.004), mechanical (OR 1.79, p = 0.002), and renal (OR 1.64, p = 0.015) complications had higher odds of new morbidity. Other races (Pacific Islanders, and Native Americans) (OR 2.89, p = 0.013), longer duration of ECLS (OR 1.002, p = 0.002), and mechanical complications (OR 1.67, p = 0.026) had higher odds of unfavorable outcomes. In conclusion, in our multi-center 9-year ECLS experience, 56% survived, 40% developed new morbidity, and 84% had favorable outcome. Future studies with larger populations could help identify modifiable risk factors that could help guide clinicians in this fragile patient population.

Utility of Cerebral Microvascular Imaging in Infants Undergoing ECMO

PURPOSE

Infants who require extracorporeal membrane oxygenation (ECMO) therapy have an increased risk of neurological complications and mortality. Microvascular imaging (MVI) is an advanced Doppler technique that allows high-resolution visualization of microvasculature in the brain. We describe the feasibility and utility of MVI for the evaluation of cerebral microvascular perfusion in patients undergoing ECMO.

METHODS

We retrospectively analyzed brain MVI scans of neonates undergoing ECMO. Two pediatric radiologists qualitatively assessed MVI scans to determine the presence or absence of tortuosity, symmetry, heterogeneity, engorgement, and hypoperfusion of the basal ganglia-thalamus (BGT) region, as well as the presence or absence of white matter vascular engorgement and increased peri-gyral flow in the cortex. We tested the association between the presence of the aforementioned brain MVI features and clinical outcomes.

RESULTS

We included 30 patients, 14 of which were male (46.7%). The time of ECMO duration was 11.8 ± 6.9 days. The most prevalent microvascular finding in BGT was lenticulostriate vessel tortuosity (26/30, 86.7%), and the most common microvascular finding in the cortex was increased peri-gyral flow (10/24, 41.7%). Cortical white matter vascular engorgement was significantly associated with the presence of any poor outcome as defined by death, seizure, and/or cerebrovascular events on magnetic resonance imaging (p = 0.03).

CONCLUSION

MVI is a feasible modality to evaluate cerebral perfusion in infants undergoing ECMO. Additionally, evidence of white matter vascular engorgement after ECMO cannulation could serve as a predictor of poor outcomes in this population.

Transcranial Doppler Ultrasound, a Review for the Pediatric Intensivist

The use of transcranial Doppler ultrasound (TCD) is increasing in frequency in the pediatric intensive care unit. This review highlights some of the pertinent TCD applications for the pediatric intensivist, including evaluation of cerebral hemodynamics, autoregulation, non-invasive cerebral perfusion pressure/intracranial pressure estimation, vasospasm screening, and cerebral emboli detection.

Multimodal Neurologic Monitoring in Children With Acute Brain Injury

Children with acute neurologic illness are at high risk of mortality and long-term neurologic disability. Severe traumatic brain injury, cardiac arrest, stroke, and central nervous system infection are often complicated by cerebral hypoxia, hypoperfusion, and edema, leading to secondary neurologic injury and worse outcome. Owing to the paucity of targeted neuroprotective therapies for these conditions, management emphasizes close physiologic monitoring and supportive care. In this review, we will discuss advanced neurologic monitoring strategies in pediatric acute neurologic illness, emphasizing the physiologic concepts underlying each tool. We will also highlight recent innovations including novel monitoring modalities, and the application of neurologic monitoring in critically ill patients at risk of developing neurologic sequelae.

Utility of cephalic drains in infants receiving extracorporeal membrane oxygenation

INTRODUCTION

The addition of cephalic drains (CDs) in extracorporeal membrane oxygenation (ECMO) to augment venous drainage may offer benefit, though their use is varied. Our objective was to describe our institution's experience with CDs including flow rates and patency. We also compared complication rates between patients with and without a CD.

METHODS

This retrospective cohort study included infants <12 months of age cannulated for ECMO between January 1, 2010 and September 30, 2019 at a single institution. Flow data were obtained for those with a CD. Demographic and complication rates were obtained for all.

RESULTS

Of 264 patients in the final cohort, 220 (83%) had a CD of which 93.2% remained patent to decannulation. CDs typically provided 30% or more of ECMO flow throughout the ECMO run. The median time to CD clot was 139 h (range 48-635 h). Patients with a clotted CD had longer ECMO runs than those whose CD remained patent (median 382 h [IQR 217-538] vs 139 h [IQR 91-246], p < 0.001). Survival to discharge was lower for those with clotted versus patent CD (14% vs 70%, p < 0.001). Mechanical complications were more common in patients with CD (p = 0.005). Seizures were more common in those without a CD (p = 0.021).

CONCLUSIONS

In this cohort, the majority of CDs placed remained patent at decannulation and provided substantial additional venous drainage. Mechanical problems were common in patients with CDs, but without clinical sequelae. Further study is warranted to elucidate CD impact on short- and long-term outcomes.

ECMO in neonates: The association between cerebral hemodynamics with neurological function

Extracorporeal membrane oxygenation (ECMO) is a superior life support technology, commonly employed in critical patients with severe respiratory or hemodynamic failure to provide effective respiratory and circulatory support, which is especially recommended for the treatment of critical neonates. However, the vascular management of neonates with veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is still under controversy. Reconstruction or ligation for the right common carotid artery (RCCA) after ECMO is inconclusive. This review summarized the existed studies on hemodynamics and neurological function after vascular ligation or reconstruction hoping to provide better strategies for vessel management in newborns after ECMO. After reconstruction, the right cerebral blood flow can increase immediately, and the normal blood supply can be restored rapidly. But the reconstructed vessel may be occluded and stenotic in long-term follow-ups. Ligation may cause lateralization damage, but there could be no significant effect owing to the establishment of collateral circulation. The completion of the circle of Willis, the congenital anomalies of cerebral or cervical vasculature, the duration of ECMO, and the vascular condition at the site of arterial catheterization should be assessed carefully before making the decision. It is also necessary to follow up on the reconstructed vessel sustainability, and the association between cerebral hemodynamics and neurological function requires further large-scale multi-center studies.

Clinical applications of transcranial Doppler in non-trauma critically ill children: a scoping review

BACKGROUND

Many applications of transcranial Doppler (TCD) as a diagnosis or monitoring tool have raised interest in the last decades. It is important that clinicians know when and how to perform TCD in this population, what parameter to assess and monitor and how to interpret it.

OBJECTIVE

This review aims to describe the emerging clinical applications of TCD in critically ill children excluding those suffering from trauma.

METHODS

Databases Web of Science, Cochrane and PubMed were searched in May 2020. We considered all publications since the year 2000 addressing the use of TCD as a prognostic, diagnostic or follow-up tool in children aged 0 to 15 years admitted to intensive care or emergency units, excluding neonatology and traumatic brain injury. Two independent reviewers selected 82 abstracts and full-text articles from the 2011 unique citations identified at the outset.

RESULTS

TCD provides crucial additional information at bedside about cerebrovascular hemodynamics. Many clinical applications include the diagnosis and management of various medical and surgical neurologic conditions (central nervous system infections, arterial ischemic stroke, subarachnoid hemorrhage and vasospasm, brain death, seizures, metabolic disease, hydrocephalus) as well as monitoring the impact systemic conditions on brain perfusion (hemodynamic instability, circulatory assistance).

CONCLUSION

To conclude, TCD has become an invaluable asset for non-invasive neuromonitoring in critically ill children excluding those suffering from trauma. However, the scope of TCD remains unclearly defined yet and reference values in critically ill children are still lacking.

Neurological Complications of Veno-Arterial Extracorporeal Membrane Oxygenation: A Retrospective Case-Control Study

Background: To explore the epidemiology, clinical features, risk indicators, and long-term outcomes of neurological complications caused by veno-arterial extracorporeal membrane oxygenation (V-A ECMO).

Methods: We retrospectively analyzed 60 adult patients who underwent V-A ECMO support in our unit from February 2012 to August 2020. These patients were separated into the neurological complications group (NC group) and the non-neurological complications group (nNC group). The differences in basic data and ECMO data between the two groups were compared. The data of long-term neurological prognosis were collected by telephone follow-up.

Results: Thirty-nine patients (65.0%) had neurological complications. There were significant differences between the two groups in terms of median age, hypertension, median blood urea nitrogen, median troponin I (TNI), median lactic acid, pre-ECMO percutaneous coronary intervention, continuous renal replacement therapy (CRRT), median Sequential Organ Failure Assessment score, median Acute Physiology and Chronic Health Evaluation II score, median peak inspiratory pressure, median positive end expiratory pressure, and median fresh frozen plasma (P < 0.05). The median Intensive Care Unit length of stay (ICU LOS), 28-day mortality, median post-ECMO vasoactive inotropic score, non-pulsate perfusion (NP), and median ECMO duration of the NC group were significantly higher than those of the nNC group (P < 0.05). Furthermore, multiple logistic regression analysis revealed that TNI (P = 0.043), CRRT (P = 0.047), and continuous NP > 12 h (P = 0.043) were independent risk indicators for neurological complications in patients undergoing ECMO. Forty-four patients (73.3%) survived after discharge, and 38 patients (63.3%) had Cerebral Performance Category score of 1–2. And there were significant differences between the two groups in long-term neurological outcomes after discharge for 6 months (P < 0.05).

Conclusion: The incidence of neurological complications was higher in patients undergoing V-A ECMO and was closely related to adverse outcomes (including ICU LOS and 28-day mortality). TNI, CRRT, and continuous NP > 12 h were independent risk indicators for predicting neurological complications in ECMO supporting patients. And the neurological complications of patients during ECMO support had significant adverse effect on long-term surviving and neurological outcomes of patients after discharge for 6 months.

Practice Recommendations for Transcranial Doppler Ultrasonography in Critically Ill Children in the Pediatric Intensive Care Unit: A Multidisciplinary Expert Consensus Statement

Transcranial Doppler ultrasonography (TCD) is being used in many pediatric intensive care units (PICUs) to aid in the diagnosis and monitoring of children with known or suspected pathophysiological changes to cerebral hemodynamics. Standardized approaches to scanning protocols, interpretation, and documentation of TCD examinations in this setting are lacking. A panel of multidisciplinary clinicians with expertise in the use of TCD in the PICU undertook a three-round modified Delphi process to reach unanimous agreement on 34 statements and then create practice recommendations for TCD use in the PICU. Use of these recommendations will help to ensure that high quality TCD images are captured, interpreted, and reported using standard nomenclature. Furthermore, use will aid in ensuring reproducible and meaningful study results between TCD practitioners and across PICUs.

Challenges of acute phase neuroimaging in VA-ECMO, pitfalls and alternative imaging options

Large vessel occlusion in patients on ECMO is challenging to appreciate clinically secondary to sedation or induced paralysis, thus placing more emphasis on neurovascular imaging. However, emergent CTA and CTP are both inaccurate and unreliable in ECMO patients due to altered circuitry and interference with normal physiologic hemodynamics. In this review, the utility of DSA is discussed in evaluating the altered hemodynamics of VA-ECMO circuits and patency of major vasculature. In addition, the potential use of TCD in ECMO patients is discussed.

Association Between Arterial Carbon Dioxide Tension and Clinical Outcomes in Venoarterial Extracorporeal Membrane Oxygenation

OBJECTIVES

The manipulation of arterial carbon dioxide tension is associated with differential mortality and neurologic injury in intensive care and cardiac arrest patients; however, few studies have investigated this relationship in patients on venoarterial extracorporeal membrane oxygenation. We investigated the association between the initial arterial carbon dioxide tension and change over 24 hours on mortality and neurologic injury in patients undergoing venoarterial extracorporeal membrane oxygenation for cardiac arrest and refractory cardiogenic shock.

DESIGN

Retrospective cohort analysis of adult patients recorded in the international Extracorporeal Life Support Organization Registry.

SETTING

Data reported to the Extracorporeal Life Support Organization from all international extracorporeal membrane oxygenation centers during 2003-2016.

PATIENTS

Adult patients (≥ 18 yr old) supported with venoarterial extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 7,168 patients had sufficient data for analysis at the initiation of venoarterial extracorporeal membrane oxygenation, 4,918 of these patients had arterial carbon dioxide tension data available at 24 hours on support. The overall in-hospital mortality rate was 59.9%. A U-shaped relationship between arterial carbon dioxide tension tension at extracorporeal membrane oxygenation initiation and in-hospital mortality was observed. Increased mortality was observed with a arterial carbon dioxide tension less than 30 mm Hg (odds ratio, 1.26; 95% CI, 1.08-1.47; p = 0.003) and greater than 60 mm Hg (odds ratio, 1.28; 95% CI, 1.10-1.50; p = 0.002). Large reductions (> 20 mm Hg) in arterial carbon dioxide tension over 24 hours were associated with important neurologic complications: intracranial hemorrhage, ischemic stroke, and/or brain death, as a composite outcome (odds ratio, 1.63; 95% CI, 1.03-2.59; p = 0.04), independent of the initial arterial carbon dioxide tension.

CONCLUSIONS

Initial arterial carbon dioxide tension tension was independently associated with mortality in this cohort of venoarterial extracorporeal membrane oxygenation patients. Reductions in arterial carbon dioxide tension (> 20 mm Hg) from the initiation of extracorporeal membrane oxygenation were associated with neurologic complications. Further prospective studies testing these associations are warranted.

Neurological complications during veno-venous extracorporeal membrane oxygenation: Does the configuration matter? A retrospective analysis of the ELSO database

Background

Single- (SL) and double-lumen (DL) catheters are used in clinical practice for veno-venous extracorporeal membrane oxygenation (V-V ECMO) therapy. However, information is lacking regarding the effects of the cannulation on neurological complications.

Methods

A retrospective observational study based on data from the Extracorporeal Life Support Organization (ELSO) registry. All adult patients included in the ELSO registry from 2011 to 2018 submitted to a single run of V-V ECMO were analyzed. Propensity score (PS) inverse probability of treatment weighting estimation for multiple treatments was used. The average treatment effect (ATE) was chosen as the causal effect estimate of outcome. The aim of the study was to evaluate differences in the occurrence and the type of neurological complications in adult patients undergoing V-V ECMO when treated with SL or DL cannulas.

Results

From a population of 6834 patients, the weighted propensity score matching included 6245 patients (i.e., 91% of the total cohort; 4175 with SL and 20,270 with DL cannulation). The proportion of patients with at least one neurological complication was similar in the SL (306, 7.2%) and DL (189, 7.7%; odds ratio 1.10 [95% confidence intervals 0.91–1.32]; p = 0.33). After weighted propensity score, the ATE for the occurrence of least one neurological complication was 0.005 (95% CI − 0.009 to 0.018; p = 0.50). Also, the occurrence of specific neurological complications, including intracerebral hemorrhage, acute ischemic stroke, seizures or brain death, was similar between groups. Overall mortality was similar between patients with neurological complications in the two groups.

Conclusions

In this large registry, the occurrence of neurological complications was not related to the type of cannulation in patients undergoing V-V ECMO.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03533-5.

Transcranial Doppler Use in Non-traumatic Critically Ill Children: A Multicentre Descriptive Study

Background: The use and perceived value of transcranial Doppler (TCD) scope in paediatric critical care medicine has not been extensively documented. Objective: To describe the use of TCD to assess non-traumatic brain injury in patients admitted to four paediatric intensive care units (PICUs) in France. Methods: We prospectively included all children (aged under 18) assessed with inpatient TCD between November 2014 and October 2015 at one of the four PICUs. The physicians completed a questionnaire within 4 h of performing TCD. Results: 152 children were included. The primary diagnosis was neurological disease in 106 patients (70%), including post ischemic-anoxic brain insult (n = 42, 28%), status epilepticus (n = 19, 13%), and central nervous system infection/inflammation (n = 15, 10%). TCD was the first-line neuromonitoring assessment in 110 patients (72%) and was performed within 24 h of admission in 112 patients (74%). The most common indications for TCD were the routine monitoring of neurological disorders (n = 85, 56%) and the detection of asymptomatic neurological disorders (n = 37, 24). Concordance between the operator's interpretation of TCD and the published normative values was observed for 21 of the 75 (28%) TCD abnormal findings according to the published normative values. The physicians considered that TCD was of value for the ongoing clinical management of 131 (86%) of the 152 patients. Conclusion: TCD is commonly used in French PICUs and tends to be performed early after admission on patients with a broad range of diseases. The physicians reported that the TCD findings often helped their clinical decision making. In view of the subjectivity of bedside interpretation, true TCD contribution to clinical care remains to be determined. Objective studies of the impact of TCD on patient management and clinical outcomes are therefore warranted.

Multiscale modeling of blood flow to assess neurological complications in patients supported by venoarterial extracorporeal membrane oxygenation

Computational blood flow models in large arteries elucidate valuable relationships between cardiovascular diseases and hemodynamics, leading to improvements in treatment planning and clinical decision making. One such application with potential to benefit from simulation is venoarterial extracorporeal membrane oxygenation (VA-ECMO), a support system for patients with cardiopulmonary failure. VA-ECMO patients develop high rates of neurological complications, partially due to abnormal blood flow throughout the vasculature from the VA-ECMO system. To better understand these hemodynamic changes, it is important to resolve complex local flow parameters derived from three-dimensional (3D) fluid dynamics while also capturing the impact of VA-ECMO support throughout the systemic arterial system. As high-resolution 3D simulations of the arterial network remain computationally expensive and intractable for large studies, a validated, multiscale model is needed to compute both global effects and high-fidelity local hemodynamics. In this work, we developed and demonstrated a framework to model hemodynamics in VA-ECMO patients using coupled 3D and one-dimensional (1D) models (1D→3D). We demonstrated the ability of these multiscale models to simulate complex flow patterns in specific regions of interest while capturing bulk flow throughout the systemic arterial system. We compared 1D, 3D, and 1D→3D coupled models and found that multiscale models were able to sufficiently capture both global and local hemodynamics in the cerebral arteries and aorta in VA-ECMO patients. This study is the first to develop and compare 1D, 3D, and 1D→ 3D coupled models on the larger arterial system scale in VA-ECMO patients, with potential use for other large scale applications.

Brain magnetic resonance imaging in adult survivors of extracorporeal membrane oxygenation

Despite the common occurrence of neurologic complications in patients with extracorporeal membrane oxygenation (ECMO), data on magnetic resonance imaging (MRI) findings in adult ECMO are limited. We aimed to describe the MRI findings of patients after ECMO cannulation. Records of patients who underwent ECMO from September 2017 to June 2019 were reviewed. MRI studies were performed using multiplanar sequences consisting of T1-, T2-weighted, fluid attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and susceptibility weighted images (SWI). Of the 78 adult patients who underwent ECMO, 26 (33%) survived. Of 26, eight patients (31%) had MRI studies, with a median age of 47 years (interquartile range [IQR]: 25-57). The median ECMO support time was 8 days (IQR: 4-25) and the median time from decannulation to MRI was 12 days (IQR: 1-34). Five (63%) of eight patients had ischemic infarcts; 4 (50%) had cerebral microhemorrhage; 2 (25%) had intracranial hemorrhage; and 1 (13%) had thoracic cord ischemic infarct. There were no patients with normal MRI. All patients underwent transcranial Doppler (TCD). Four of 8 (50%) showed presence of microemboli with TCD; 3 of 4 (75%) had ischemic infarcts; and 1 of 4 (25%) had presence of multiple cerebral microhemorrhages on MRI. All ischemic infarcts had diffuse pattern of punctate to small lesions for ECMO survivors. The location of cerebral microhemorrhages included lobar (n = 4, 100%), deep (n = 2, 50%), and both (n = 2, 50%). Of the MRI studies, cerebrovascular related lesions were the most frequent, with punctate ischemic infarct being the most common type that may be associated with TCD microemboli. The results of the study suggest that subclinical cerebral lesions are commonly found in patients with ECMO support. Further research is needed to understand long-term effect of these cerebral lesions.

Neurological Monitoring and Complications of Pediatric Extracorporeal Membrane Oxygenation Support

Extracorporeal membrane oxygenation is extracorporeal life support for life-threatening cardiopulmonary failure. Since its introduction, the use of extracorporeal membrane oxygenation has expanded to patients with more complex comorbidities without change in patient mortality rates. Although many patients survive, significant neurological complications like seizures, ischemic strokes, and intracranial hemorrhage can occur during extracorporeal membrane oxygenation care. The risks of these complications often add to the complexity of decision-making surrounding extracorporeal membrane oxygenation support. In this review, we discuss the pathophysiology and incidence of neurological complications in children supported on extracorporeal membrane oxygenation, factors influencing the incidence of these complications, commonly used neurological monitoring modalities, and outcomes for this complex patient population. We discuss the current literature on the use of electroencephalography for both seizure detection and monitoring of background electroencephalographic changes, in addition to the use of less commonly used imaging modalities like transcranial Doppler. We summarize the knowledge gaps and the lack of clinical consensus guidelines for managing these potentially life-changing neurological complications. Finally, we discuss future work to further understand the pathophysiology of extracorporeal membrane oxygenation-related neurological complications.

Transcranial Doppler Ultrasound During Critical Illness in Children: Survey of Practices in Pediatric Neurocritical Care Centers

OBJECTIVES

The scope of transcranial Doppler ultrasound in the practice of pediatric neurocritical care is unknown. We have surveyed pediatric neurocritical care centers on their use of transcranial Doppler and analyzed clinical management practices.

DESIGN

Electronic-mail recruitment with survey of expert centers using web-based questionnaire.

SETTING

Survey of 43 hospitals (31 United States, 12 international) belonging to the Pediatric Neurocritical Care Research Group.

PATIENTS

None.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A 67% (29/43) hospital-response rate. Of these centers, 27 reported using transcranial Doppler in the PICU; two hospitals opted out due to lack of transcranial Doppler availability/use. The most common diagnoses for using transcranial Doppler in clinical care were intracranial/subarachnoid hemorrhage (20 hospitals), arterial ischemic stroke (14 hospitals), and traumatic brain injury (10 hospitals). Clinical studies were carried out and interpreted by credentialed individuals in 93% (25/27) and 78% (21/27) of the centers, respectively. A written protocol for performance of transcranial Doppler in the PICU was available in 30% (8/27 hospitals); of these, two of eight hospitals routinely performed correlation studies to validate results. In 74% of the centers (20/27), transcranial Doppler results were used to guide clinical care: that is, when to obtain a neuroimaging study (18 hospitals); how to manipulate cerebral perfusion pressure with fluids/vasopressors (13 hospitals); and whether to perform a surgical intervention (six hospitals). Research studies were also commonly performed for a range of diagnoses.

CONCLUSIONS

At least 27 pediatric neurocritical care centers use transcranial Doppler during clinical care. In the majority of centers, studies are performed and interpreted by credentialed personnel, and findings are used to guide clinical management. Further studies are needed to standardize these practices.

Non-invasive estimation of cerebral perfusion pressure using transcranial Doppler ultrasonography in children with severe traumatic brain injury

OBJECTIVE

To identify if cerebral perfusion pressure (CPP) can be non-invasively estimated by either of two methods calculated using transcranial Doppler ultrasound (TCD) parameters.

DESIGN

Retrospective review of previously prospectively gathered data.

SETTING

Pediatric intensive care unit in a tertiary care referral hospital.

PATIENTS

Twenty-three children with severe traumatic brain injury (TBI) and invasive intracranial pressure (ICP) monitoring in place.

INTERVENTIONS

TCD evaluation of the middle cerebral arteries was performed daily. CPP at the time of the TCD examination was recorded. For method 1, estimated cerebral perfusion pressure (CPPe) was calculated as: CPPe = MAP × (diastolic flow (Vd)/mean flow (Vm)) + 14. For method 2, critical closing pressure (CrCP) was identified as the intercept point on the x-axis of the linear regression line of blood pressure and flow velocity parameters. CrCP/CPPe was then calculated as MAP-CrCP.

MEASUREMENTS AND MAIN RESULTS

One hundred eight paired measurements were available. Using patient averaged data, correlation between CPP and CPPe was significant (r = 0.78, p = < 0.001). However, on Bland-Altman plots, bias was 3.7 mmHg with 95% limits of agreement of - 17 to + 25 for CPPe. Using patient averaged data, correlation between CPP and CrCP/CPPe was significant (r = 0.59, p = < 0.001), but again bias was high at 11 mmHg with wide 95% limits of agreement of - 15 to + 38 mmHg.

CONCLUSIONS

CPPe and CrCP/CPPe do not have clinical value to estimate the absolute CPP in pediatric patients with TBI.

Outcomes of Infants Supported With Extracorporeal Membrane Oxygenation Using Centrifugal Versus Roller Pumps: An Analysis From the Extracorporeal Life Support Organization Registry

OBJECTIVES

To determine whether mortality differs between roller and centrifugal pumps used during extracorporeal membrane oxygenation in infants weighing less than 10 kg.

DESIGN

Retrospective propensity-matched cohort study.

SETTING

All extracorporeal membrane oxygenation centers reporting to the Extracorporeal Life Support Organization.

PATIENTS

All patients less than 10 kg supported on extracorporeal membrane oxygenation during 2011-2016 within Extracorporeal Life Support Organization Registry.

INTERVENTIONS

Centrifugal and roller pump recipients were propensity matched (1:1) based on predicted probability of receiving a centrifugal pump using demographic variables, indication for extracorporeal membrane oxygenation, central versus peripheral cannulation, and pre-extracorporeal membrane oxygenation patient management.

MEASUREMENTS AND MAIN RESULTS

A total of 12,890 patients less than 10 kg were supported with extracorporeal membrane oxygenation within the Extracorporeal Life Support Organization registry during 2011-2016. Patients were propensity matched into a cohort of 8,366. Venoarterial and venovenous extracorporeal membrane oxygenation runs were propensity matched separately. The propensity-matched cohorts were similar except earlier year of extracorporeal membrane oxygenation (standardized mean difference, 0.49) in the roller pump group. Within the propensity-matched cohort, survival to discharge was lower in the centrifugal pump group (57% vs 59%; odds ratio, 0.91; 95% CI, 0.83-0.99; p = 0.04). Hemolytic, infectious, limb injury, mechanical, metabolic, neurologic, pulmonary, and renal complications were more frequent in the centrifugal pump group. Hemorrhagic complications were similar between groups. Hemolysis mediated the relationship between centrifugal pumps and mortality (indirect effect, 0.023; p < 0.001).

CONCLUSIONS

In this propensity score-matched cohort study of 8,366 extracorporeal membrane oxygenation recipients weighing less than 10 kg, those supported with centrifugal pumps had increased mortality and extracorporeal membrane oxygenation complications. Hemolysis was evaluated as a potential mediator of the relationship between centrifugal pump use and mortality and met criteria for full mediation.

Cerebral Oxygenation of Premature Lambs Supported by an Artificial Placenta

An artificial placenta (AP) using venovenous extracorporeal life support (VV-ECLS) could represent a paradigm shift in the treatment of extremely premature infants. However, AP support could potentially alter cerebral oxygen delivery. We assessed cerebral perfusion in fetal lambs on AP support using near-infrared spectroscopy (NIRS) and carotid arterial flow (CAF). Fourteen premature lambs at estimated gestational age (EGA) 130 days (term = 145) underwent cannulation of the right jugular vein and umbilical vein with initiation of VV-ECLS. An ultrasonic flow probe was placed around the right carotid artery (CA), and a NIRS sensor was placed on the scalp. Lambs were not ventilated. CAF, percentage of regional oxygen saturation (rSO2) as measured by NIRS, hemodynamic data, and blood gases were collected at baseline (native placental support) and regularly during AP support. Fetal lambs were maintained on AP support for a mean of 55 ± 27 hours. Baseline rSO2 on native placental support was 40% ± 3%, compared with a mean rSO2 during AP support of 50% ± 11% (p = 0.027). Baseline CAF was 27.4 ± 5.4 ml/kg/min compared with an average CAF of 23.7 ± 7.7 ml/kg/min during AP support. Cerebral fractional tissue oxygen extraction (FTOE) correlated negatively with CAF (r = -0.382; p < 0.001) and mean arterial pressure (r = -0.425; p < 0.001). FTOE weakly correlated with systemic O2 saturation (r = 0.091; p = 0.017). Cerebral oxygenation and blood flow in premature lambs are maintained during support with an AP. Cerebral O2 extraction is inversely related to carotid flow and is weakly correlated with systemic O2 saturation.

Cerebrovascular Physiology During Pediatric Extracorporeal Membrane Oxygenation: A Multicenter Study Using Transcranial Doppler Ultrasonography

OBJECTIVES

To explore changes to expected, age-related transcranial Doppler ultrasound variables during pediatric extracorporeal membrane oxygenation.

DESIGN

Prospective, observational, multicenter study.

SETTING

Tertiary care PICUs.

PATIENTS

Children 1 day to 18 years old requiring veno arterial extracorporeal membrane oxygenation.

METHODS

Participants underwent daily transcranial Doppler ultrasound measurement of bilateral middle cerebral artery flow velocities. Acute neurologic injury was diagnosed if seizures, cerebral hemorrhage, or diffuse cerebral ischemia was detected.

MEASUREMENTS AND MAIN RESULTS

Fifty-two children were enrolled and analyzed. In the 44 children without acute neurologic injury, there was a significant reduction in systolic flow velocity and mean flow velocity compared with predicted values over time (F [8, 434] = 60.44; p ≤ 0.0001, and F [8, 434] = 17.61; p ≤ 0.0001). Middle cerebral artery systolic flow velocity was lower than predicted on extracorporeal membrane oxygenation days 1-5, and mean flow velocity was lower than predicted on extracorporeal membrane oxygenation days 1-3. In the six infants less than 90 days old suffering diffuse cerebral ischemia, middle cerebral artery systolic flow velocity, mean flow velocity, and diastolic flow velocity from extracorporeal membrane oxygenation days 1-9 were not significantly different when compared with children of similar age in the cohort that did not suffer acute neurologic injury (systolic flow velocity F [8, 52] = 0.6659; p = 0.07 and diastolic flow velocity F [8, 52] = 1.4; p = 0.21 and mean flow velocity F [8, 52] = 1.93; p = 0.07). Pulsatility index was higher in these infants over time than children of similar age in the cohort on extracorporeal membrane oxygenation that did not suffer acute neurologic injury (F [8, 52] = 3.1; p = 0.006). No patient in the study experienced cerebral hemorrhage.

CONCLUSIONS

Flow velocities in the middle cerebral arteries of children requiring extracorporeal membrane oxygenation are significantly lower than published normative values for critically ill, mechanically ventilated, sedated children. Significant differences in measured systolic flow velocity, diastolic flow velocity, and mean flow velocity were not identified in children suffering ischemic injury compared with those who did not. However, increased pulsatility index may be a marker for ischemic injury in young infants on extracorporeal membrane oxygenation.

Neurologic Complications in the Pediatric Intensive Care Unit

PURPOSE OF REVIEW

All critical care is directed at maintaining brain health, but recognizing neurologic complications of critical illness in children is difficult, and limited data exist to guide practice. This article discusses an approach to the recognition and management of seizures, stroke, and cardiac arrest as complications of other critical illnesses in the pediatric intensive care unit.

RECENT FINDINGS

Convulsive and nonconvulsive seizures occur frequently in children after cardiac arrest or traumatic brain injury and during extracorporeal membrane oxygenation. Seizures may add to neurologic morbidity, and continuous EEG monitoring is needed for up to 24 hours for detection. Hypothermia has not been shown to improve outcome after cardiac arrest in children, but targeted temperature management with controlled normothermia and prevention of fever is a mainstay of neuroprotection.

SUMMARY

Much of brain-directed pediatric critical care is empiric. Recognition of neurologic complications of critical illness requires multidisciplinary care, serial neurologic examinations, and an appreciation for the multiple risk factors for neurologic injury present in most patients in the pediatric intensive care unit. Through attention to the fundamentals of neuroprotection, including maintaining or restoring cerebral perfusion matched to the metabolic needs of the brain, combined with anticipatory planning, these complications can be prevented or the neurologic injury mitigated.

Incidence, Outcome, and Predictors of Intracranial Hemorrhage in Adult Patients on Extracorporeal Membrane Oxygenation: A Systematic and Narrative Review

Background: Intracranial hemorrhage (ICH) is a common complication in adults treated with extracorporeal membrane oxygenation (ECMO).

Objectives: The aim of this study was to conduct a systematic review of the literature on the incidence, outcome and predictors of ECMO-associated ICH in adult patients, supplemented by a narrative review of its pathophysiology, management and future perspectives.

Methods: MEDLINE, EMBASE, Cochrane Database of Systematic Reviews and www.clinicaltrials.gov were systematically searched. Studies that reported incidence, outcome or predictors of ECMO-associated ICH in adults (≥18 years) were eligible for inclusion.

Results: Twenty five articles were included in the systematic review. The incidence of ECMO-associated ICH varied between 1.8 and 21 %. Mortality rates in ICH-cohorts varied between 32 and 100 %, with a relative risk of mortality of 1.27–4.43 compared to non-ICH cohorts. An increased risk of ICH was associated with ECMO-duration, antithrombotic therapy, altered intrinsic coagulation, renal failure, need of blood products, rapid hypercapnia at ECMO initiation, and even pre-ECMO morbidity.

Conclusions: ICH is a common complication in adults treated with ECMO and associated with increased mortality. Treating an ICH during ECMO represents a balance between pro- and anticoagulatory demands. Neurosurgical treatment is associated with severe morbidity, but has been successful in selected cases. Future studies should aim at investigating the validity and feasibility of non-invasive monitoring in early detection of ECMO-associated ICH.

Cerebral Pathophysiology in Extracorporeal Membrane Oxygenation: Pitfalls in Daily Clinical Management

Extracorporeal membrane oxygenation (ECMO) is a life-saving technique that is widely being used in centers throughout the world. However, there is a paucity of literature surrounding the mechanisms affecting cerebral physiology while on ECMO. Studies have shown alterations in cerebral blood flow characteristics and subsequently autoregulation. Furthermore, the mechanical aspects of the ECMO circuit itself may affect cerebral circulation. The nature of these physiological/pathophysiological changes can lead to profound neurological complications. This review aims at describing the changes to normal cerebral autoregulation during ECMO, illustrating the various neuromonitoring tools available to assess markers of cerebral autoregulation, and finally discussing potential neurological complications that are associated with ECMO.

Hyperoxia and Hypocapnia During Pediatric Extracorporeal Membrane Oxygenation: Associations With Complications, Mortality, and Functional Status Among Survivors

OBJECTIVES

To determine the frequency of hyperoxia and hypocapnia during pediatric extracorporeal membrane oxygenation and their relationships to complications, mortality, and functional status among survivors.

DESIGN

Secondary analysis of data collected prospectively by the Collaborative Pediatric Critical Care Research Network.

SETTING

Eight Collaborative Pediatric Critical Care Research Network-affiliated hospitals.

PATIENTS

Age less than 19 years and treated with extracorporeal membrane oxygenation.

INTERVENTIONS

Hyperoxia was defined as highest PaO2 greater than 200 Torr (27 kPa) and hypocapnia as lowest PaCO2 less than 30 Torr (3.9 kPa) during the first 48 hours of extracorporeal membrane oxygenation. Functional status at hospital discharge was evaluated among survivors using the Functional Status Scale.

MEASUREMENTS AND MAIN RESULTS

Of 484 patients, 420 (86.7%) had venoarterial extracorporeal membrane oxygenation and 64 (13.2%) venovenous; 69 (14.2%) had extracorporeal membrane oxygenation initiated during cardiopulmonary resuscitation. Hyperoxia occurred in 331 (68.4%) and hypocapnia in 98 (20.2%). Hyperoxic patients had higher mortality than patients without hyperoxia (167 [50.5%] vs 48 [31.4%]; p < 0.001), but no difference in functional status among survivors. Hypocapnic patients were more likely to have a neurologic event (49 [50.0%] vs 143 (37.0%]; p = 0.021) or hepatic dysfunction (49 [50.0%] vs 121 [31.3%]; p < 0.001) than patients without hypocapnia, but no difference in mortality or functional status among survivors. On multivariable analysis, factors independently associated with increased mortality included highest PaO2 and highest blood lactate concentration in the first 48 hours of extracorporeal membrane oxygenation, congenital diaphragmatic hernia, and being a preterm neonate. Factors independently associated with lower mortality included meconium aspiration syndrome.

CONCLUSIONS

Hyperoxia is common during pediatric extracorporeal membrane oxygenation and associated with mortality. Hypocapnia appears to occur less often and although associated with complications, an association with mortality was not observed.

Point-of-care ultrasound in pediatric anesthesiology and critical care medicine

Ultrasound has increasingly become a clinical asset in the hands of the anesthesiologist and intensivist who cares for children. Though many applications for ultrasound parallel adult modalities, children as always are not simply small adults and benefit from the application of ultrasound to their management in various ways. Body composition and size are important factors that affect ultrasound performance in the child, as are the pathologies that may uniquely afflict children and aspects of procedures unique to this patient population. Ultrasound simplifies vascular access and other procedures by visualizing structures smaller than those in adults. Maturation of the thoracic cage presents challenges for the clinician performing pulmonary ultrasound though a greater proportion of the thorax can be seen. Moreover, ultrasound may provide unique solutions to sizing the airway and assessing it for cricothyroidotomy. Though cardiac ultrasound and neurosonology have historically been performed by well-developed diagnostic imaging services, emerging literature stresses the utility of clinician ultrasound in screening for pathology and providing serial observations for monitoring clinical status. Use of ultrasound is growing in clinical areas where time and diagnostic accuracy are crucial. Implementation of ultrasound at the bedside will require institutional support of education and credentialing. It is only natural that the pediatric anesthesiologist and intensivist will lead the incorporation of ultrasound in the future practice of these specialties.

Improving Long-Term Outcomes After Extracorporeal Membrane Oxygenation: From Observational Follow-Up Programs Toward Risk Stratification

Since the introduction of extracorporeal membrane oxygenation (ECMO), more neonates and children with cardiorespiratory failure survive. Interest has therefore shifted from reduction of mortality toward evaluation of long-term outcomes and prevention of morbidity. This review addresses the changes in ECMO population and the ECMO-treatment that may affect long-term outcomes, the diagnostic modalities to evaluate neurological morbidities and their contributions to prognostication of long-term outcomes. Most follow-up data have only become available from observational follow-up programs in neonatal ECMO-survivors. The main topics are discussed in this review. Recommendations for long-term follow up depend on the presence of neurological comorbidity, the nature and extent of the underlying disease, and the indication for ECMO. Follow up should preferably be offered as standard of care, and in an interdisciplinary, structured and standardized way. This permits evaluation of outcome data and effect of interventions. We propose a standardized approach and recommend that multiple domains should be evaluated during long-term follow up of neonates and children who needed extracorporeal life support.

Severe Respiratory Failure, Extracorporeal Membrane Oxygenation, and Intracranial Hemorrhage

OBJECTIVES

For patients supported with veno-venous extracorporeal membrane oxygenation, the occurrence of intracranial hemorrhage is associated with a high mortality. It is unclear whether intracranial hemorrhage is a consequence of the extracorporeal intervention or of the underlying severe respiratory pathology. In a cohort of patients transferred to a regional severe respiratory failure center that routinely employs admission brain imaging, we sought 1) the prevalence of intracranial hemorrhage; 2) survival and neurologic outcomes; and 3) factors associated with intracranial hemorrhage.

DESIGN

A single-center, retrospective, observational cohort study.

SETTING

Tertiary referral severe respiratory failure center, university teaching hospital.

PATIENTS

Patients admitted between December 2011 and February 2016.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Three hundred forty-two patients were identified: 250 managed with extracorporeal support and 92 managed using conventional ventilation. The prevalence of intracranial hemorrhage was 16.4% in extracorporeal membrane oxygenation patients and 7.6% in conventionally managed patients (p = 0.04). Multivariate analysis revealed factors independently associated with intracranial hemorrhage to be duration of ventilation (d) (odds ratio, 1.13 [95% CI, 1.03-1.23]; p = 0.011) and admission fibrinogen (g/L) (odds ratio, 0.73 [0.57-0.91]; p = 0.009); extracorporeal membrane oxygenation was not an independent risk factor (odds ratio, 3.29 [0.96-15.99]; p = 0.088). In patients who received veno-venous extracorporeal membrane oxygenation, there was no significant difference in 6-month survival between patients with and without intracranial hemorrhage (68.3% vs 76.0%; p = 0.350). Good neurologic function was observed in 92%.

CONCLUSIONS

We report a higher prevalence of intracranial hemorrhage than has previously been described with high level of neurologically intact survival. Duration of mechanical ventilation and admission fibrinogen, but not exposure to extracorporeal support, are independently associated with intracranial hemorrhage.

Transcranial Doppler Identification of Neurologic Injury during Pediatric Extracorporeal Membrane Oxygenation Therapy

BACKGROUND

We used transcranial Doppler to examine changes in cerebral blood flow velocity in children treated with extracorporeal membrane oxygenation. We examined the association between those changes and radiologic, electroencephalographic, and clinical evidence of neurologic injury.

METHODS

This was a retrospective review and prospective observational study of patients 18 years old and younger at a single university children's hospital. Transcranial Doppler studies were obtained every other day during the first 7 days of extracorporeal membrane oxygenation, and 1 additional study following decannulation, in conjunction with serial neurologic examinations, brain imaging, and 6- to 12-month follow-up.

RESULTS

The study included 27 patients, the majority (26) receiving veno-arterial extracorporeal membrane oxygenation. Transcranial Doppler velocities during extracorporeal membrane oxygenation were significantly lower than published values for age-matched healthy and critically ill children across different cerebral arteries. Neonates younger than 10 days had higher velocities than expected. Blood flow velocity increased after extracorporeal membrane oxygenation decannulation and was comparable with age-matched critically ill children. There was no significant association between velocity measurements of individual arteries and acute neurologic injury as defined by either abnormal neurologic examination, seizures during admission, or poor pediatric cerebral performance category. However, case analysis identified several patients with regional and global increases in velocities that corresponded to neurologic injury including stroke and seizures.

CONCLUSIONS

Cerebral blood flow velocities during extracorporeal membrane oxygenation deviate from age-specific normal values in all major cerebral vessels and across different age groups. Global or regional elevations and asymmetries in flow velocity may suggest impending neurologic injury.

Resistive Index Variability in Anterior Cerebral Artery Measurements During Daily Transcranial Duplex Sonography: A Predictor of Cerebrovascular Complications in Infants Undergoing Extracorporeal Membrane Oxygenation?

OBJECTIVES

The purpose of this study was to determine the value of resistive index (RI) variability in predicting cerebrovascular complications during extracorporeal membrane oxygenation (ECMO).

METHODS

This retrospective study included 36 infants treated by ECMO. The RI was measured on daily transfontanellar duplex sonography, obtained first without fontanel compression and then after gentle compression with the transducer. The age at ECMO cannulation, sex, gestational age at birth, method of delivery, indication, and type and duration of ECMO were recorded.

RESULTS

There was a statistically significant difference in RI variability in infants who developed cerebrovascular complications as opposed to those who did not (P = .002). Resistive index variability of 10% or greater on any day was associated with an increased risk for cerebrovascular complications (P = .0482; χ² = 3.9). Variability in the first 5 days was significantly higher than on following days (P < .0001). The age at ECMO cannulation showed a significant difference, with mean ± SD values of 1.1 ± 0.9 days in the complications group and 2.7 ± 2.2 days in the no-complications group (P = .043).

CONCLUSIONS

Resistive index variability of 10% or greater on any day had a statistically significant risk of cerebrovascular complication development. Extracorporeal membrane oxygenation cannulation at younger than 3 days conferred an increased risk of cerebrovascular complications.

Plasma Biomarkers of Brain Injury as Diagnostic Tools and Outcome Predictors After Extracorporeal Membrane Oxygenation

OBJECTIVE

To determine if elevations in plasma brain injury biomarkers are associated with outcome at hospital discharge in children who require extracorporeal membrane oxygenation.

DESIGN

Prospective observational study.

SETTING

Single tertiary-care academic center.

PARTICIPANTS

Eighty children who underwent extracorporeal membrane oxygenation between June 2010 and December 2013.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured six brain injury biomarkers (glial fibrillary acidic protein, monocyte chemoattractant protein 1/chemokine (C-C motif) ligand 2, neuron-specific enolase, S100b, intercellular adhesion molecule-5, and brain-derived neurotrophic factor) daily during extracorporeal membrane oxygenation, using an electrochemiluminescent multiplex assay. We recorded clinical, neuroimaging, and extracorporeal membrane oxygenation course data. We analyzed the association of biomarker concentrations with favorable versus unfavorable outcome at hospital discharge. Favorable outcome was defined as Pediatric Cerebral Performance Category 1, 2, or no change from baseline. Patients had a median age of 3 days (interquartile range, 1 d-10 mo), and 56% were male. Thirty-three of 80 (41%) had unfavorable outcome, and 22 of 70 (31%) had abnormal neuroimaging findings during or after extracorporeal membrane oxygenation. Peak concentrations were significantly higher in patients with unfavorable outcome than in those with favorable outcome for glial fibrillary acidic protein (p = 0.002), monocyte chemoattractant protein 1/chemokine (C-C motif) ligand 2 (p = 0.030), neuron-specific enolase (p = 0.006), and S100b (p = 0.015) and in patients with versus without abnormal neuroimaging findings for glial fibrillary acidic protein (p = 0.001) and intercellular adhesion molecule-5 (p = 0.001). The area under the receiver operator characteristic curve for unfavorable outcome was 0.73 for a noncollinear biomarker combination. After removing collinear biomarkers, the adjusted odds ratios for unfavorable outcome were 2.89 (95% CI, 1.09-7.73) for neuron-specific enolase, using a cutoff of 62.0 ng/mL, and 2.15 (95% CI, 1.06-4.38) for glial fibrillary acidic protein, using a cutoff of 0.46 ng/mL.

CONCLUSIONS

Elevated plasma brain injury biomarker concentrations during the extracorporeal membrane oxygenation course are associated with unfavorable outcome and/or the presence of neuroimaging abnormalities. Combinations of brain-specific proteins increase the sensitivity and specificity for outcome prediction.

Neuromonitoring During Extracorporeal Membrane Oxygenation: A Systematic Review of the Literature

OBJECTIVE

Neurologic injury remains a significant morbidity and risk factor for mortality in critically ill patients undergoing extracorporeal membrane oxygenation. Our goal was to systematically review the literature on the use of neuromonitoring methods during extracorporeal membrane oxygenation.

DATA SOURCES

Electronic searches of PubMed, CINAHL, EMBASE, Web of Science, Cochrane, and Scopus were conducted in March 2014, using a combination of medical subject heading terms and text words to define concepts of extracorporeal life support, neurologic monitoring techniques, evaluation, and outcomes.

STUDY SELECTION

Studies were selected based on inclusion and exclusion criteria defined a priori.

DATA EXTRACTION

Two authors reviewed all citations independently. A standardized data extraction form was used to construct evidence tables by neuromonitoring method. Evidence was graded using the Oxford Evidence-Based Medicine scoring system.

DATA SYNTHESIS

Of 3,459 unique citations, 39 studies met the inclusion criteria. Study designs were retrospective observational cohort studies (n = 20), prospective observational studies (n = 17), case-control studies (n = 2), and no interventional studies. Most studies evaluated newborns (n = 30). Extracorporeal membrane oxygenation neuromonitoring methods included neuroimaging (head ultrasound) (n = 12); intermittent, conventional, multichannel electroencephalography (n = 5); 1- to 2-channel amplitude-integrated electroencephalography (n = 2); Doppler ultrasound (n = 7); cerebral oximetry (n = 6); plasma brain injury biomarkers (n = 4); and other (n = 3). All evidence was graded 2B-4, with the majority of studies graded 3B (20/39 studies) and 4 (10/39 studies). Due to the heterogeneity of the studies included, aggregate analysis was not possible.

CONCLUSIONS

Data supporting the use and effectiveness of current neuromonitoring methods are limited. Most studies have modest sample sizes, are observational in nature, and include patient populations that are of different ages and pathologies, with very limited data for pediatric and adult ages. Well-designed studies with adequate power and standardized short- and long-term outcomes are needed to develop guidelines for neuromonitoring and ultimately neuroprotection in patients on extracorporeal membrane oxygenation.

Effects of intra-aortic balloon pump on cerebral blood flow during peripheral venoarterial extracorporeal membrane oxygenation support

Background

The addition of an intra-aortic balloon pump (IABP) during peripheral venoarterial extracorporeal membrane oxygenation (VA ECMO) support has been shown to improve coronary bypass graft flows and cardiac function in refractory cardiogenic shock after cardiac surgery. The purpose of this study was to evaluate the impact of additional IABP support on the cerebral blood flow (CBF) in patients with peripheral VA ECMO following cardiac procedures.

Methods

Twelve patients (mean age 60.40 ± 9.80 years) received VA ECMO combined with IABP support for postcardiotomy cardiogenic shock after coronary artery bypass grafting. The mean CBF in the bilateral middle cerebral arteries was measured with and without IABP counterpulsation by transcranial Doppler. The patients provided their control values. The mean CBF data were divided into two groups (pulsatile pressure greater than 10 mmHg, P group; pulsatile pressure less than 10 mmHg, N group) based on whether the patients experienced cardiac stun. The mean cerebral blood flow in VA ECMO (IABP turned off) alone and VA ECMO with IABP support were compared using the paired t test.

Results

All of the patients were successfully weaned from VA ECMO, and eight patients survived to discharge. The addition of IABP to VA ECMO did not change the mean CBF (251.47 ± 79.28 ml/min vs. 251.30 ± 79.47 ml/min, P = 0.96). The mean CBF was higher in VA ECMO alone than in VA ECMO combined with IABP support in the N group (257.68 ± 97.21 ml/min vs. 239.47 ± 95.60, P = 0.00). The addition of IABP to VA ECMO support increased the mean CBF values significantly compared with VA ECMO alone (261.68 ± 82.45 ml/min vs. 244.43 ± 45.85 ml/min, P = 0.00) in the P group.

Conclusion

These results demonstrate that an IABP significantly changes the CBF during peripheral VA ECMO, depending on the antegrade blood flow by spontaneous cardiac function. The addition of an IABP to VA ECMO support decreased the CBF during cardiac stun, and it increased CBF without cardiac stun.